Particularly on women's rights and women's-health issues, Sanders' and Clinton's positions are seemingly identical — both support equal-pay bills, both favor universal pre-kindergarten education programs, and both support paid family leave. They're also fairly close together on issues like immigration and some aspects of campaign finance.

But despite some similarities, Sanders remains a challenger with legitimate claims to run as a progressive alternative to Clinton.

Here's where Hillary Clinton and Bernie Sanders stand on several key issues: